Extinguishing Class D fires, that is combustible metal fires, is exceptionally difficult. There were no known liquid firefighting agents prior to the invention which are capable of extinguishing Class D fires. According to the invention, it is possible to extinguish burning metal fires since the formulation according to the invention is capable of absorbing a tremendous amount of heat without turning into a gas and separating as other liquid agents do when they come in contact with burning combustible metals. For the formulation according to the invention, the heat absorption ability is approximately 7.7 million BTUs per pound, compared to 1,142 BTUs per pound for water. It may be applied with any standard mobile or fixed firefighting equipment utilizing a wide angle fog nozzle, or sprinkler system head.
The liquid formulation for use as a Class D firefighting agent according to the invention consists essentially of a mixture of: A linear alkylbenzene sulfonate, non-ionic detergent and lauric superamide detergent mixture comprising about 39-67 percent of the total mass of the formulation. Vitamin B-6 in the amount of 1-3 percent by weight of the detergent mixture. Sodium chloride in the amount of about 25-41 percent by weight of the detergent mixture. Bicarbonate of soda in the amount of about 3-18 percent by weight of the detergent mixture. 0-4 percent by weight of the detergent mixture coloring and perfuming agents. And, a volume of water large enough only to provide effective mixing of the other components of the formulation and insufficiently large to interfere with the use of the formulation as an effective Class D firefighting agent. The detergent mixture component of the formulation preferably comprises, by volume: about 41-45% linear alkylbenzene sulfonate (LAS), about 8-12% isooctylphenyl polyethoxyethanol (IP), about 0-4% polyoxyethylene sorbitan monooleate (PSM), about 8-12% lauric diethanolamide (LD), about 0.5-1% monoethanolamide superamides (MS), and about 26-30% water. In a preferred formulation according to the invention vitamin B-6 is in an amount of about 1%, bicarbonate about 8%, and sodium chloride about 37%.
The invention also comprises a method of formulating the Class D liquid firefighting agent according to the invention, and extinguishing a combustible metal fire. In the method of formulating a Class D firefighting agent, the following steps are practiced: adding amounts of materials consisting essentially of vitamin B-6, sodium chloride, and bicarbonate of soda, with small amounts of coloring and perfuming agents if desired, effective when, in formulation, to put out a Class D fire, to a minimum amount of water sufficient to facilitate mixing of the components; mixing the vitamin B-6, sodium chloride, bicarbonate of soda, and water together so that substantially no lumps exist and a generally homogeneous slurry is provided; and then mixing the slurry with the detergent mixture so as to provide a homogeneous Class D firefighting agent.
A method of extinguishing a combustible metal fire according to the invention comprises the following step applying directly to the fire a liquid composition consisting essentially of a major part of detergent mixture of linear alkylbenzolyate sulfonate, non-ionic detergent and lauric superamide, and amounts of vitamin B-6, sodium chloride, bicarbonate of sodium, with minimal amounts of water, with small amounts of coloring and perfuming agents, if desired, effective when, in formulation, to put out a combustible metal fire, by slowing down the detergent mixture emulsification rate; densifying and increasing the heat absorption capability of the detergent mixture; agitating and stabilizing the detergent mixture; and densifying and preventing separation and detonation of the detergent mixture when exposed to burning metal.
It is the primary object of the present invention to provide an effective Class D firefighting liquid composition, and method of formulation and fire extinguishment utilizing the same. This and other objects of the invention will become clear from the detailed description, and the appended claims.